This study aims to test the efficacy of cognitive-behavioural therapy for insomnia (CBTI) and CBT for depression (CBTD) in reducing insomnia and depression severity in adolescents with comorbid diagnosis, and to examine the effects of CBT-I and CBT-D on quality of life, daytime-related symptoms and functioning (e.g. sleepiness, fatigue) as well as subjective and objective sleep measures.